I/O

Introduction

xpp::io provides reactive async I/O for non-blocking file descriptors, plus a structured error type shared across all I/O modules (net, fs, etc.).

#include <xpp/io/async_fd.h>
#include <xpp/io/error.h>

xpp::EventLoop loop;
xpp::WaitScope scope(loop);

int sv[2];
socketpair(AF_UNIX, SOCK_STREAM | SOCK_NONBLOCK, 0, sv);
xpp::io::AsyncFd io(sv[0]);

write(sv[1], "hello", 5);
char buf[64] = {};
ssize_t n = xpp::io::read(io, buf, sizeof(buf)).await();

Modules

• AsyncFd — Reactive I/O wrapper: register fd once, readable()/writable() as Promise<void>, fast-path read()/write().

• I/O Error — io::Error: niche-optimized (4-byte) error type with ErrorKind, raw_os_error(), raw_xerrno(). Mirrors Rust's std::io::Error.

• Utilities — read_all and copy: duck-typed template functions. Coroutine loops with 8KB stack buffers (C++20) or struct+move fallback (C++11).

• BufReader — BufReader<R>: buffered async reader. Reduces per-call Promise overhead for small reads.

• BufWriter

• Take

• Empty

• Sink

• Duplex

• Simplex

• Repeat

• Join

• Split — BufWriter<W>: buffered async writer. Coalesces small writes, explicit flush().